Radio receiver tuning mechanism



Dec. 31, 1940. c. J. VAN mow 2,226,751- RADIO RECEIVER TUNING MECHANISM I I I Filed June 3, 1958 TUNING CONDENSER INVENTOR. CARE: AN VAN LOON A TTURNEY.

Patented Dec. 31, 1940 PATENT OFFICE RADIO'RECEIVER TUNIN MECHAMSM Care] Jan van Loon, Eindhoven, Netherlands, assignor, by mesne assignments, to Radio Corporation of America, New York,N. 12, a corporation of Delaware Application June 3, 1938, Serial No. 211,492 In Germany July 26, 1937 2 Claims.

The invention relates to a radio-receiving apparatus wherein a difierential mechanism is connected between the spindle of the tuning condenser and the driving mechanism for this condenser. One of the members of this mechanism which are movable with respect to the driving shaft of the difierential mechanism may cooperate in this case witha braking device whereas the other member of this mechanism which is movable with respect to said shaft actuates the spindle of the tuning condenser.

The construction according to the invention is particularly advantageous if in such apparatus tuning is effected with the aid of a motor. In this case the tuning condenser must be stopped at once after the correct tuning to some station or other has been effected. The velocities of rotation of the movable members of the differential mechanism may be altered or compensated in this case in some way or other with the result that the transmission which is generally present between the shaft of the driving mechanism and the spindle of the tuning condenser is altered or suppressed respectively. For example, as has been mentioned already, one of the members of the differential mechanism may co-operate with a braking device by which said member is held fast when the apparatus is not tuned to any station. Those parts of the mechanism which transmit the motion of one shaft to the other,

thus acquire'the opportunity to push ofi against this stationary member and to actuate the other movable member. With the latter member is coupled in this case, for example with the aid of a cable or of gear wheels, the spindle of the tuning condenser so that this condenser is turned as long as the one movable member of the differ-.- ential mechanism is stationary. When one comes within reach of some station or other, the braking device becomes inoperative. The bodies which transmit the motion of oneshaft to the other, can nolonger push off in this case on the originally stationary member, which is now, however, in motion, that is to say they can bring about hardly any coupling. Due to the friction the tuning condenser remains stationary and the above-mentionedbodies, which remain in motion owing to the driving shaft, utilise the member coupled with the tuning condenser as a pushingof! member so that now the member co-operating with the braking device starts rotating. If it is desired to leave the station once chosen, the braking device is actuated anew with the result that the-initial state is restored. Thus it is conlili sequently possible to stop the spindle of the tuning condenser at once although the driving shaft may still remain in rotary motion.

In one favorable form of construction of the device according to the invention braking is effected with the aid of an electro-rnagnetic brake. Relatively to ordinary (rotatory) magnetic couplings theadvantage is obtained that the exciting coil may remain immovable so that a material simplification in the construction of the apparatusis obtained.

The differential mechanism may be formed in different ways; it may consist, for example, of a The invention'will be explained more fully with reference to the accompanying drawing wherein Figs. 1 and 2 represent diagrammatically the above-described device.

A shaft which is journalled in bearings I and 2 is connected to the driving member. In denotes the spindle of the tuning condensers represented by the block III. A bush 4 is free to rotate on the shaft 3, said bush having apertures 5 into which flt balls 6. At one end said bush is provided with a pulley I on which runs a cord or cable 8 which is also led over a pulley 9 which is rigidly mounted on the spindle l0. 0n the inside as well as on the outside the balls 6 protrude from the member 4 and, being clamped with a certain pressure, they run on the one hand in a path H formed in the shaft 3 and on the other hand in a path I! provided in a member l3. The latter member co-operates with an electromagnetic brake H which is formed by a core I! surrounded by a plurality of wire-turns l6.

The device operates as follows:

When the driving shaft 3 rotates and when, upon operating the receiving apparatus, one is out of reach of some station or other the core l5 of the brake I4 is drawn against the brake disc l3 due to the magnetic effect of the electric current flowing through the wire turns 5, the disc l3 being consequently stationary. Rotation of the shaft 3 results in that the balls 6 which are clamped with a certain pressure, start rotating and push of! during this rotation against the stationary path i2 provided in the disc I 3. Owing since the latter has become movable. Due to the friction in the drive mechanism of the tuning,

condenser the spindle I I and therefore also the bush 4 remain stationary. This results in that the rotating balls 6 impart to the disc I3 a rotatory motion the direction of which is opposite to that of the shaft 3. If it is desired to leave the station to which the apparatus. is once tuned, the coil Ii must be excited anew owing to which the disc i3 is stopped'again. Then the pulley I is caused to rotate again with the. result that also the tuning condenser is carried along with it.

Although the construction represented may also be successfully utilised in those cases in which the shaft 3 is actuated by hand, itls particularly advantageous if, as has previously been observed, the shaft 3 has mounted on it a motor which serves to actuate the condenser so that when tuning is effected this motor may be allowed to run down without any disadvantage.

What I claimis: v

1. In control apparatus for a radio' receiver provided with timing mechanism, a driving shaft adapted to control adjustment of the tuning mechanism, gear means loosely mounted on said shaft and having an extension bushing which is provided with a ball cage, a race way formed in the driving shaft, a member having a second raceway formed'therein and adapted to cooperate with the balls inthe ball cage, the loosely mounted gear means and its extension remaining stationary and said member assuming rotary motion so long as the driving shaft is in motion,

means adapted to arrest the motion of said member' whereby the loosely mounted gear means is .mechanlcally coupled to the driving shaft, and additional gear means coupled to the first mentinned gear, means for driving the tuning mechanism.

2. Incontrol apparatus for a radio receiver provided with tuning mechanism, a driving shaft adapted to control adjustment of the tuning ,mechanism, a pulley loosely mounted on said shaft, a second pulley rigidly connected to the tuning mechanism, a cable entrained about said two pulleys, the loosely mounted pulley having an extension bushing which is provided with a ball cage, a raceway in the driving shaft, a.

' member whereby the loosely mounted pulley is mechanically coupled to the driving shaft to thereby drive the tuning mechanism.

CAREL JAN VAN LooN. 

